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Learn All About Wollastonite

Wollastonite

A versatile industrial mineral.

What is Wollastonite?

Wollastonite is comprised chemically of calcium, silicon, and oxygen. Natural wollastonite may contain trace or minor amounts of various metal ions such as aluminum, iron, magnesium, potassium, and sodium. It is rarely found by itself and generally contains other minerals like calcite, garnet, and diopside that are removed during processing.

Fun Facts

  • In the 7th and 8th centuries, the Chinese were the first to use Wollastonite to make porcelain.

Where to Find Wollastonite

Uses for Wollastonite

Plastics In plastics, wollastonite improves the durability of composites. It also enhances electrical insulating properties, adds fire resistance, and improves dimensional stability. Finer particle size grades provide improved scratch and impact resistance compared to other materials. 
Construction Wollastonite is a substitute for asbestos in fire-resistant building products used in the construction industry. It is used in interior and exterior construction boards, roof tiles, shaped insulation products, sheets, panels, and sidings. As a functional additive, wollastonite improves flexural and impact strengths. Its low thermal conductivity and high aspect ratio structure also makes wollastonite an attractive addition for applications requiring fire resistance. 
Paints & Coatings In coatings, wollastonite particles act as a good flattening agent allowing paint to settle out after application to produce a dry film of uniform thickness. The interlocking particles improve toughness and durability of paints with excellent tint retention, scrub, and corrosion and weather resistance. High brightness and whiteness reduce pigment loa, reducing pigment costs. Wollastonite can also act as a pH buffer for improved in-can paint stability over long periods of time.
Ceramics Wollastonite is used in a variety of ceramic applications, including ceramic glazes and bodies, enamels, frits, fluxes, and sanitary ware. It is also used in alkaline glaze formulations, improving the strength of glazes. 
Metal Production In metallurgical applications, wollastonite is used due to its low water solubility and low loss on ignition. Wollastonite is commonly added to formulated powders for steel casting and welding. The addition of Wollastonite to metallurgical fluxes provides ready fusibility, good insulating qualities, and low viscosity. When molten steel is poured continuously from a ladle or tundish, a wollastonite casting powder is applied to maintain surface defects, prevent oxidation of the steel, and to lubricate the mold wall.
Friction Due to its physical structure and non-hazardous properties, wollastonite is used as a reinforcing additive in many friction applications. It is also a partial/full replacement for asbestos, milled fibers, chopped glass, and synthetic materials. Its primary application is in semi-metallic and non-asbestos formulations for truck blocks, drum linings, disc pads, and friction paper. 

Related Resources

USGS Wollastonite Mineral Commodity Summary

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